<template>
    <div id="child">
        <h2>我是子组件</h2>
        {{}}
    </div>

</template>
<script>
    import { ref } from 'vue'
    export default {
        name: 'Child',
        components: {

        },
        async setup() {
            let sum = ref(0)
            let p = new Promise((reslove, reject) => {
                setTimeout(() => {
                    reslove({ sum })
                }, 3000)
            })
            return await p
        }

    }

</script>

<style>
    #child {
        width: 3000px;
        background-color: pink;
    }
</style>